The tombstone lifetime in an Active Directory forest determines
how long a deleted object (called a “tombstone”) is retained in
Active Directory Domain Services (AD DS). The tombstone lifetime is
determined by the value of the tombstoneLifetime attribute on the Directory Service object in the configuration directory partition. You can use this procedure to determine the tombstone lifetime for the forest. Membership in Domain Users, or equivalent, is
the minimum required to complete this procedure.

To determine the tombstone lifetime for the forest using ADSIEdit

For Connection Point, click Select a well known Naming Context, and then click Configuration.

If you want to connect to a different domain controller, for Computer, click Select or type a domain or server: (Server | Domain [:port]). Provide the server name or the domain name and Lightweight Directory Access Protocol (LDAP) port (389), and then click OK.

Once the Active Directory object is deleted, it is not hard deleted from a system. As you may know, Active Directory makes the object hidden by changing its attribute isDeleted to TRUE value. Then, it drops most of the objects’ attributes, renames the object, and moves it to a special container (CN=Deleted Objects). From now on, the object has a tombstone status, and standard Active Directory utilities don’t see its presence. Then, the object is conserved within this special state for a lifetime period (60 days for Windows Server 2000/2003 and 180 days for Windows 2003 SP1/2008). This is to ensure that the information about removal was successfully replicated across the system. Once the tombstone lifetime period is over, a special process calledgarbage collectorphysically removes the object from the database.

Here comes the question. If the tombstone object was not physically deleted within a certain amount of time, would it be possible to recover (reanimate) it? The short answer is yes.